Particle counting apparatus having automatic display and threshold setting

ABSTRACT

Particle counting apparatus especially adapted for blood cell counting and which is essentially automatic in operation. Coded sample flasks are employed in conjunction with a counter display to automatically set the appropriate decimal point for corresponding red or white count magnitude and to also provide automatic threshold settings for red and white cell counts.

United States Patent Estelle et al. [4 1 Apr. 4, 1972 s41 PARTICLECOUNTING APPARATUS UNITED STATES PATENTS HAVING AUTOMATIC DISPLAY AND3,020,749 2/1962 Cropper et al. ..235/92 SH THRESHOLD SETTING 2,674,6754/1954 Lambert ..340/280 [72] Inventors: Weems E. Estelle, Southport;Pasquale M. 3441352 4/ 1969 Hughesm "356/39 x Petrucci, Orange, both ofConn. Primary Examiner Daryl Cook [73] Assignee: General Science Corp.,Bridgeport, Conn. Assistant Examiner-Joseph The,

Attorney-Joseph Weingarten [22] Filed: Apr. 28, 1970 21 Appl. N0.:32,583 [57] ABSTRACT Particle counting apparatus especially adapted forblood cell 52 us. 0 .235/92 PC, 235/92 R, 235/92 EA, and essemauy r340/280 324/71 CP 356/39 Coded sample flasks are employed in con unctionwith a Int Cl H03k 21/18 counter display to automatically set theappropriate decimal point for corresponding red or white count magnitudeand to [58] Field of Search "235/92 EA'92 92 92 also provide automaticthreshold settings for red and white 235/643, 61 DP, 94; 340/280;356/39; 324/71 CP cell counts.

[56] References Cited 5 Claims, 5 Drawing Figures LOGIC CIRCUITRYPATVENITEDAPR 4 m2 3,654,439

' SHEETIUFZ 32 34 @5 16 & 5

LOGIC CIRCUITRY DISPLAY INDICATORS 44 T4 I 46 Fig. 1.

INVIIN'H )RS WEEMS E. ESTELLE PASQUALE M PE TRUCCI PATENTEDAFR 41972SHEET 2 0F 2 IN VEN'I )RS WEEMS E. ESTELLE I v PASOUALE M PETRUCCIORNFYS PARTICLE COUNTING APPARATUS HAVING AUTOMATIC DISPLAY ANDTHRESHOLD SETTING FIELD OF THE INVENTION BACKGROUND OF THE INVENTIONSystems are known for counting particles suspended in a liquid, a majorapplication of such systems being the counting of red and white bloodcells. In general, such particle counting systems include a pair ofelectrodes disposed within a fluid path and having an aperture disposedtherebetween through which the particle-containing fluid flows. Theimpedance of the fluid path as sensed by the electrodes is materiallyaltered by the presence of a particle within the aperture, giving riseto electrical pulses which can be electrically counted and whichcorrespond to the number of particles passing through the aperture.Means are usually employed for metering a known volume ofparticle-containing liquid such that a particle count for a known volumeof liquid can be provided.

Particle counting systems of known construction are usually quitecomplex and rather expensive, and the high cost of conventional systemslimits their availability to many who would otherwise have use for suchsystems. In addition, known systems often require many manipulativesteps during operation in order to provide the requisite analysis, andare often difficult to calibrate. Moreover, the aperture through whichparticles are caused to flow is usually formed with a glass vessel, andis not easily accessible for cleaning or adjustment.

SUMMARY OF THE INVENTION In accordance with the present invention, asophisticated and yet relatively simple particle counting system isprovided which is especially adapted for blood cell counting and whichis substantially automatic in operation. The system includes codedsample flasks or bottles which are operative to automatically set theappropriate threshold for red of white cell counting and to also set anappropriate decimal point of an output counter to display a correctcount magnitude.

A system embodying the invention includes a conductivity cell having apair of electrodes and an easily adjustable and interchangeable aperturedisposed between the electrodes and sized to accommodate the blood cellsor other particles under analysis. A photosensitive metering techniqueis employed to determine the volume of liquid which is to be analyzed.The passage of particles through the aperture of the conductivity cellalters the impedance of the path through the aperture, and the change inimpedance causes a corresponding change in voltage level which is sensedby a high input impedance, low noise, high gain amplifier. Thresholddetection circuitry is provided to discriminate against pulses below apredetermined threshold level caused by noise and other spuriousconditions.

A separate sample flask is provided for red cell and white cell samples,and each flask is uniquely coded to automatically set respectivethreshold levels and count magnitude displays upon insertion of a flaskinto the system. Insertion of a red cell flask into the system causes anappropriate threshold level to be set and also causes illumination of anappropriate decimal point indicator and red cell count indicator fordisplay of the proper count magnitude for red cells. Insertion of awhite cell flask similarly determines the count magnitude and thresholdlevel suitable for a white cell count.

DESCRIPTION OF THE DRAWINGS The invention will be more fully understoodfrom the following detailed description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a diagrammatic representation of a particle counting systemaccording to the invention;

FIG. 2 is a pictorial view, partly in section, illustrating aconductivity cell embodied in the invention;

FIG. 3 is a pictorial view, partly in phantom, of a particle countingsystem according to the invention;

FIG. 4 is a cutaway pictorial view of the sample flask coding apparatusembodied in the invention; and

FIG. 5 is a pictorial view of a sample flask according to the invention.

DETAILED DESCRIPTION OF THE INVENTION A particle counting system whichis especially adapted for counting blood cells is illustrated indiagrammatic form in FIG. 1. The particles to be counted are suspendedwithin a liquid contained within a sample flask l0, and fluid is drawnfrom flask 10 into the system by means of a tube I2. Theparticle-containing fluid is drawn from flask 10 by way of tube 12 tothe input orifice of a conductivity cell 14 which includes a pair ofelectrodes with an aperture disposed therebetween and through which thefluid to be analyzed flows. The conductivity cell per se will bedescribed in detail hereinafter.

Conductivity cell 14 is coupled to a flow tube 16 which terminates in awaste bottle 18. A suction pump 20 is also coupled to waste bottle 18through a-suitably sealed stopper 22 and is operative to draw samplefluid from flask 10 through conductivity cell 14 and flow tube 16 foranalysis. A pair of electrodes 24 are disposed within waste bottle 18and are coupled to logic circuitry 26 for the detection of apredetermined upper level of waste fluid within bottle 18 to preventoverflow of waste fluid from the bottle and to also prevent the entry ofwaste fluid into suction pump 20.

A first photosensor 28 is disposed adjacent flow tube 16 at apredetermined position along the length thereof and a second photosensor30 is similarly disposed with respect to flow tube 16 in a positiondownstream from first photosensor 28. Flow tube 16 is formed of asuitable light transmissive material such as glass and a pair of lightsources 32 and 34 are arranged in operative association with respectivephotosensors 28 and 30. The photosensorsare connected to logic circuitry26 and are employed to provide electro-optical metering of the volume ofliquid to be analyzed. In the absence of fluid flowing within tube 16,photosensors 28 and 30 receive light from respective sources 32 and 34.During the passage of fluid within tube 16, however, the respectivephotosensors 28 and 30 do not receive light from their respectiveillumination sources. An electrical output signal is thus provided tologic circuitry 26 by photosensors 28 and 30 depending upon the presenceof fluid at the sensor locations. The particle counting operation iscommenced and terminated by gating signals provided by thiseIectro-optical metering system. The passage of fluid within tube 16past photosensor 28 causes a signal to be applied to logic circuitry 26to commence a counting operation, while the counting operation isterminated upon receipt of a signal from photosensor 30. In this manner,a counting run is accomplished on a metered volume of liquid determinedby the internal dimensions of flow tube 16 and the distance between themetering photosensors 28 and 30. The photosensitive metering techniqueitself is described in detail in copending US Pat. application Ser. No.809,332, now US Pat. No. 3,577,162, entitled Automatic Particle CountingSystem and assigned to Contraves AG.

The electrodes 36 and 38 of conductivity cell 14 are connected to aninput amplifier 40 which is a high input impedance, low noise, high gainoperational amplifier. The output of amplifier 40 is coupled to logiccircuitry 26 and the logic circuitry is operative to provide an outputindication of particle count on a suitable display 42 and to energizesuitable alarm indicators 44. Operating controls 46 are coupled to logiccircuitry 26 for enabling system operation.

The conductivity cell through which the sample fluid is caused to flowand in which the changes in impedance caused by the presence ofparticles within an aperture are detected is illustrated moreparticularly in FIG. 2. The cell 14 is of generally cylindricalconfiguration and typically is formed of a plastic material such asplexiglass or other polycarbonate plastic which is inert to the fluidsbeing analyzed and which is electrically insulative. An aperture support50, also typically formed of the same plastic material, is supportedwithin a cylindrical opening coaxially provided at one end of the cellbody 51 and is securely fitted therein such as by O-rings 54. Anaperture through which the particle-containing fluid is caused to flowis formed within a ruby element 56 disposed within the side of support50, with the aperture in alignment with an input passage 58 whichcommunicates with input tube 60. A visual marking 53 is provided on anend of aperture support 50 and is located to indicate aperture alignmentwhen the marking is facing vertically upward.

The aperture within ruby 56 also communicates with an opening 61 formedin the inner end of support 50 and which in turn communicates with acoaxial passage 62 formed within cell body 51. The electrode 36 isdisposed within passage 58 and has an end adjacent the aperture element56 and is connected to an electrical connector 64 formed within body 51.The second electrode 38 is disposed within the opening 61 formed in theend of support 50 and terminates in a second electrical connector 66also formed within body 51. Electrodes 36 and 38 are typically formed ofplatinum or other metal inert to the fluid under analysis. Connectors 64and 66 are coupled by suitable interconnecting wires to input amplifier40, as illustrated in FIG. 1 and to a source of excitation voltage. Theflow tube 16 is coupled to cell 14 by means of a coaxial opening 68formed in the end of body 51 opposite to support 50 and also containingO-rings 70 for sealing. A passage 72 is coupled to fluid passage 62 andincludes an enlarged end portion or port 74 which is cooperative with aplunger 76 (FIG. 1) to provide venting of the cell. The plunger 76 iscoupled to the operated by an electrically driven solenoid 78 which isenergized by logic circuitry 26.

The construction of conductivity cell 14 permits the easy adjustment ofthe metering aperture within the fluid passage and also permitsrelatively easy cleaning and replacement of the aperture within thecell. The entire cell which is easily installed and removed from thesystem, is electrically connected by means of connectors 64 and 66, andfluid coupled by simple installation of the cell onto an end of flowtube 16 and of input tube 12 to input passage 60. During operation,fluid containing particles to be counted is drawn through passage 60,aperture element 56 and thence via passage 62 into flow tube 16. Ventport 74 is closed by plunger 76 during an analytical run so that fluidis drawn by suction pump through the system for the counting ofparticles therein. After a count has been accomplished, plunger 76 isautomatically withdrawn from the associated port 74 to cause air to bedrawn into the cell by operation of pump 20. The system is automaticallypurged after completion of a counting run and is thus in condition for asubsequent analytical run.

Automatic purging of fluid from the cell and the system after ananalytical run offers major advantages over particle counting systems ofconventional design. As discussed, opening of the conductivity cell ventafter a counting run causes air to be drawn into the cell, withconsequent purging of fluid within passages 61 and 62 of cell 14 andwithin flow tube 16. As a result of this purging operation, no fluidremains within the otherwise conductive path formed between electrodes36 and 38 and the aperture disposed therebetween, and thus no conductionbetween electrodes occurs An excitation voltage applied to the cellelectrodes need not therefore be removed, as in conventional systems,since no fluid is present to permit conduction. Excitation is thuscontinuously applied to the electrodes when the system is energized butconduction within the conductivity cell occurs only during an analyticrun.

The absence of conduction after the system is vented also preventselectrolysis and consequent production of gas bubbles during the timebetween runs. Such lack of conduction also permits the use of smallerelectrodes as the conductivity of the electrodes is not materiallydiminished by formation of gas bubbles on the surface thereof, such ascan occur to a greater extent in conventional systems. It should benoted that although residual fluid may remain by capillary action withininput passage 58, this residual fluid is not analyzed during asubsequent run since the actual fluid to be analyzed will flow throughthe cell aperture before a start signal is provided by photosensor 28.

The novel system is packaged within a compact housing which is of a sizeand configuration adapted for desk top operation. The general packagingarrangement is illustrated in FIG. 3. The conductivity cell 14 and itsassociated flow tube 16 are arranged in the illustrated embodiment onthe righthand side of the cabinet 86 with metering photosensors 28 and30 and associated light sources 32 and 34 being contained withinrespective housings 31 and 33 disposed around flow tube 16. Tube 16 iscoupled via tubing 80 to waste bottle 18 which is also coupled viatubing 82 to suction pump 20 and associated flow regulator 84 forproviding a uniform flow rate. The sample flask 10 is inserted withinthe system in the manner illustrated with input tube 12 disposed withinflask 10 for withdrawal of fluid therefrom into cell 14.

The instrument cabinet 86 includes a section on the righthand sidethereof having an opening for simple insertion of sample flask l0, andan upper opening for easy access to aperture support 50 of conductivitycell 14 for the adjustment or replacement of the metering aperture. Anozzle is coupled from pump 20 to the front panel of housing 86 toprovide a source of positive air pressure for blowing out support 50 andthe aperture therein. Support50 is placed coaxially onto nozzle 95 toclear the aperture. The controls and indicators are contained oninstrument housing 86 and include a count control 90, calibrate control92, verify indicator 94, on-off control 96 and waste indicator 98. Inthe illustrated embodiment, the controls are of the selfilluminatingpushbutton type.

The particle count is displayed on a three digit electromechanicalcounter which includes digital output indicator wheels 100; a whiteblood cell indicator 102 and red blood cell indicator 104 are providedto denote which cell count is being displayed and to display theappropriate multiplier for the cell count. Fiberoptic or other lighttransmitting cables 106 and 108 are respectively coupled from the lampsassociated with indicators 102 and 104 to positions between the digitsof indicator 100 to provide selective decimal point indication dependingupon whether a red blood cell count or a white blood cell count is beingperformed. As will be described, the decimal point is automatically setby insertion of an appropriate red cell or white cell flask 10 into thesystem.

The counter assembly and the decimal point coding arrangement isillustrated in greater detail in FIG. 4. The electrornechanical counteris itself well-known and includes digit wheels 100 driven by actuatingrelays. The respective digits being displayed and visible through asuitable window on the instrument housing. The indicators 102 and 104include a respective appropriately labeled window, as illustrated, and arespective associated light source 103 and 105 disposed therebelow.Fiberoptic cable 106 is coupled between the light source 103 and aposition between the second and third digit wheels 100 of the counter.Fiberoptic cable 108 is coupled between light source 105 and a positionbetween the first and second digit wheels of the counter. The lightsources 103 and 105 are electrically connected to microswitch 112 whichincludes an actuating arm 113 adapted to be selectively engaged by asample flask 10 inserted within the input opening of the cabinet 86.With switch 112 in one position, indicator 102 is illuminated as isdecimalpoint 116 to provide display of a white cell count magnitude.With switch 112 in its second position, indicator 104 and associateddecimal point 114 are illuminated to provide suitable display of a redcell count magnitude.

The sample flask 10 is selectively coded for red and white cellcounting. The red cell counting flask is coded as illustrated in FIG. 4with a flange 110 formed on the end thereof near the noule 111 andoperative to engage the switch arm 113 to cause setting of switch 112 toa position to enable red cell indicator 104 and decimal point 114. Thesample flask 10a (FIG. 5) employed for white cell counting does notinclude the end flange 110, and as a result, with a white sample flaskinserted within the instrument, switch 112 remains in a second positioncausing illumination of white blood cell indicator 102 and associateddecimal point 116. For convenience of use, the sample flasks can includea handle 115 and can be color coded for red cell and white cellcounting. Typically the red cell and white cell flasks are respectivelyred and white, and can be respectively prediluted to a predetermineddegree such that only a measured quantity of blood need be supplied tothe respective flasks to prepare a sample for analysis.

The input tube 116 which is inserted within the sample flask is attachedto a block 117 which is pivotally mounted for rotation about an axisdefined by mounting screws on the sides thereof. Tube 116 communicateswith a passage provided through block 117 and is coupled to cell 14 viaa flexible tube 118. In the absence of the flask within the housing,block 117 is maintained in a vertical position by a spring member 119.As a result, input tube 116 extends forwardly in a substantiallyhorizontal disposition for easy insertion into nozzle 111 of a sampleflask. After a flask is placed onto tube 116 and is seated within theopening provided within housing 86, block 117 and tube 116 are rotatedas illustrated to accommodate for the angular disposition of the inputtube within flask 10.

It is not intended to limit the invention by what has been particularlyshown and described, except as indicated in the appended claims.

What is claimed is:

1. In a particle counting system for counting blood cells suspended in afluid including an aperture through which particle-containing fluid iscaused to flow, threshold detection circuitry to discriminate againstpulses below a predetermined threshold level, means for generating anelectrical pulse for each blood cell passing through said aperture,means for counting said pulses above said predetermined threshold leveland operative to provide an indication of the number of blood cellsrepresented by said electrical pulses above said predetermined thresholdlevel within a predetermined volume of fluid, apparatus comprising:

a display having a plurality of digit indicators, first and seconddecimal point indicators associated with said digit indicators and redcell and white cell indicators for respectively indicating a numberwhich represents the multiplier of an associated cell count;

respective sample flasks for containing liquid for analysis and having acoded portion formed thereon for uniquely coding a red cell flask and awhite cell flask;

a receptacle adapted to receive a sample flask inserted therein andhaving means operative in response to the coded portion of said flask toset said decimal point indicator and multiplier indicator correspondingto the type of cells to be analyzed, and also operative to set theappropriate threshold level in said particle counting system inaccordance with the type of cells to be analyzed.

2. Apparatus according to claim 1 wherein said multiplier indicatorseach include an indicator panel containing a visual inscription of thecorresponding multiplier thereon and a light source for illuminatingsaid indicator panel; and

wherein said decimal point indicators each include a light conductingrod coupled between a respective decimal point position associated withsaid digit indicators and a respective one of said light sources.

3. Apparatus according to claim 1 wherein said receptacle means includesa switch having an arm disposed within said receptacle in a position tobe selectively engaged by the coded portion of said sample flasks.

4. Apparatus according to claim 3 wherein said sample flasks are each ofgenerally rectangular configuration having said coded portion on an endthereof adapted to selectively engage said switch arm.

5. Apparatus according to claim 3 wherein each of said flasks is ofelongated configuration and having a spout formed on one end thereoffrom which fluid is drawn for analysis, said coded portion being on theend thereof near said spout, the

presence or absence of a flange formed on said coded portionrepresenting the identity of cells to be analyzed and selectivelyactuating said switch arm accordingly to appropriately set said decimalpoint and multiplier indicators.

1. In a particle counting system for counting blood cells suspended in afluid including an aperture through which particle-containing fluid iscaused to flow, threshold detection circuitry to discriminate againstpulses below a predetermined threshold level, means for generating anelectrical pulse for each blood cell passing through said aperture,means for counting said pulses above said predetermined threshold leveland operative to provide an indication of the number of blood ceLlsrepresented by said electrical pulses above said predetermined thresholdlevel within a predetermined volume of fluid, apparatus comprising: adisplay having a plurality of digit indicators, first and second decimalpoint indicators associated with said digit indicators and red cell andwhite cell indicators for respectively indicating a number whichrepresents the multiplier of an associated cell count; respective sampleflasks for containing liquid for analysis and having a coded portionformed thereon for uniquely coding a red cell flask and a white cellflask; a receptacle adapted to receive a sample flask inserted thereinand having means operative in response to the coded portion of saidflask to set said decimal point indicator and multiplier indicatorcorresponding to the type of cells to be analyzed, and also operative toset the appropriate threshold level in said particle counting system inaccordance with the type of cells to be analyzed.
 2. Apparatus accordingto claim 1 wherein said multiplier indicators each include an indicatorpanel containing a visual inscription of the corresponding multiplierthereon and a light source for illuminating said indicator panel; andwherein said decimal point indicators each include a light conductingrod coupled between a respective decimal point position associated withsaid digit indicators and a respective one of said light sources. 3.Apparatus according to claim 1 wherein said receptacle means includes aswitch having an arm disposed within said receptacle in a position to beselectively engaged by the coded portion of said sample flasks. 4.Apparatus according to claim 3 wherein said sample flasks are each ofgenerally rectangular configuration having said coded portion on an endthereof adapted to selectively engage said switch arm.
 5. Apparatusaccording to claim 3 wherein each of said flasks is of elongatedconfiguration and having a spout formed on one end thereof from whichfluid is drawn for analysis, said coded portion being on the end thereofnear said spout, the presence or absence of a flange formed on saidcoded portion representing the identity of cells to be analyzed andselectively actuating said switch arm accordingly to appropriately setsaid decimal point and multiplier indicators.